1. Field of the Invention
The present invention relates to an image pickup unit by which an image pickup range (field) can be changed, and more particularly, to an image pickup unit which is suitable for use in a video telephone, portable terminal, computer, vehicle-on camera, monitoring camera, endoscope, etc.
2. Description of the Related Art
As readily understood from a monitoring camera etc., generally, apparatuses for enabling the change of a field are structured so as to move the whole camera (comprising the image pickup system) and, thereby, the space necessary for photographing is large and a consumption power is also large.
A video camera and a digital camera are also structured so that images in front and behind the camera can be photographed by rotating a lens in order to enable a photographed person to be easily photographed.
FIG. 18 illustrates an image pickup device disclosed in Japanese Patent Laid-Open No. 9-331473. FIG. 19 illustrates a schematic construction of a lens unit which is provided in the image pickup device. A reflecting mirror is provided between the lens unit and an image pickup medium (CCD) and a field can be changed by horizontally rotating the lens unit and the reflecting mirror.
As mentioned above, by using a structure such that a reflecting member for reflecting light from an object in an optical system is provided and a field is changed by rotating the reflecting member and the optical system on the side of the reflecting member to the object while an optical axis from the reflecting member to the image pickup medium is set as an axis, a space necessary for photographing can decrease and the image pickup device can also become compact.
FIG. 20 is a video camera disclosed in Japanese Patent Laid-Open No. 6-326900. In this video camera, a camera main body is fixed, and light from an object to be photographed is made incident to a lens by light guiding means which is provided on the front side of the lens in the camera main body. The light guiding means is mounted to a rotary member, thereby rotating at 360xc2x0 to the camera main body. Further, a video processing circuit is used and, thereby, a photographed image as an erect image can be displayed on a screen in accordance with the rotation of the light guiding means.
As described above, the reflecting member is provided in front of the optical system and the reflecting member is moved and thus a field can be changed.
According to a method disclosed in Japanese Patent Laid-Open No. 9-5650 in a decentered-axis optical system (and examples disclosed in Japanese Patent Laid-Open Nos. 8-292371, 8-292372, and 9-222561 discussed therein), a concept of a reference axis is introduced, and a constructing surface is an asymmetrical asphere and thus the structure of an optical system in which aberration is corrected efficiently is possible.
The decentered-axis optical system is called as an off-axial optical system (in the case of considering a reference axis along a ray of light passing through the center of an image  less than or the center of an object greater than  and the center of the pupil, this optical system is defined as an optical system including a curved surface  less than off-axial curved surface greater than  in which no normal of a surface at the cross point of the reference-axis and the constructing surface exists on the reference axis, and the reference axis is refracted in this case). Typically, according to the off-axial optical system, a constructing surface has a decentered axis and no vignetting occurs on the reflecting surface and, therefore, it is easy to structure the optical system using the reflecting surface. The off-axial optical system also has characteristics in that it is easy to form an integral-type optical-system by using a method of integrally forming the constructing surface.
On the other hand, a conventional optical system having only a refracting optical device has a problem that an incident pupil is located at a deep position in the optical system (in many cases) and, as an interval for a plane of incidence which is located at a position-which is the nearest to the side of the object in the case of seeing from a stop is larger, an optical effective diameter of the plane of incidence becomes larger in accordance with the enlargement in an angle of view.
In addition to the aforementioned examples, an image pickup system the which a field can be changed is indispensable for devices such as an image pickup system used for a video telephone, a digital camera provided in a computer and a portable terminal, an endoscope, and a on-vehicle camera in which an observer cannot directly move the image pickup system. The range of applications of an image pick-up system in which the field can be changed is wide.
However, in the case of using the structure such that the whole camera is moved as mentioned above, the structure is largely influenced depending on forms of devices having therein the image pickup system wherein the field can be changed. Consequently, it is necessary to design the image pickup system for every such a device. This results in an increase in costs of the image pickup system and also a rise in price of the device having therein the image pickup device. If the size of the image pickup system is large, it cannot be provided in the portable terminal, etc. Further, if a consumption power is large when the field changes, this causes an available time of the portable terminal, etc. to become short.
Accordingly, it is an object of the present invention to provide an image pickup unit for improving the flexibility of the device by extracting a common portion in an image pickup system in which an image pickup range (field) can change and by constructing the common portion as a unit and for making it advantageous to reduce costs of a variety of apparatuses in which the image pickup system is provided.
In order to accomplish the above object, according to a first aspect of the present invention, there is provided an image pickup unit having an image pickup medium, an optical system through which an image of a object is formed on the image pickup medium and, a reflecting member which is disposed at the position nearer the side of the object than the side of the optical system, to which light from the object reflects so as to be made incident to the optical system, wherein the reflecting member is driven (for example, rotated and driven), thereby the image pickup range of the image pickup medium is changed. Further, the image pickup unit has reflecting member drive means for driving the reflecting member, an interface for enabling the communication with an apparatus main body which has therein the image pickup unit and generates a signal to control an operation of the image pickup unit, and a microcomputer which transmits information on the side of the image pickup unit to the apparatus main body and controls the reflecting member drive means on the basis of the signal received from the apparatus main body.
According to a second aspect of the present invention, there is provided an image pickup unit having an image pickup medium, an optical system through which an image of a object is formed on the image pick medium, and a reflecting member which is disposed in the optical system, wherein light from the object which is incident through a portion constructing the optical system at the position nearer the side of the object than that of the reflecting member is reflected to the reflecting member and is made incident to the portion comprising the optical system at the position nearer than the side of a surface of an image than that of the reflecting member, and an orientation of image pickup field changes by driving (for example, rotating and driving) the reflecting member and the portion comprising the optical system by the image pickup medium. Further, the image pickup unit has reflecting member drive means for driving the reflecting member, an interface for enabling the communication with an apparatus main body which has therein the image pickup unit and generates a signal to control an operation of the image pickup unit, and a microcomputer which transmits information on the side of the image pickup unit to the apparatus main body and controls the reflecting member drive means on the basis of the signal received from the apparatus main body.
In other words, the image pickup unit according to this aspect of the present invention adopts the image pickup system in which the orientation of the image pickup field or the image pickup medium is changed by driving the reflecting member which is disposed at the position on the side of the object nearer than that of the optical system, alternatively, by driving the reflecting member which is disposed in the optical system and the portion constructing the optical system which is located at the position on the side of the object nearer than that of the reflecting member. Thus, the space necessary for variation in the image pickup range is small, and not only the image pickup system but also the image pickup unit including it become compact. Further, the image pickup range changes by driving the reflecting member or driving the reflecting member and only the portion comprising the optical system at the position on the side of the object nearer than that of the reflecting member and, thereby, a more power consumption decreases as compared with that in the case of rotating the whole camera or the whole image pickup system.
Moreover, the image pickup unit may have therein the drive means for driving the change in the image pickup range, the interface for enabling the communication with the apparatus main body (such as a video telephone, portable terminal, computer, on-vehicle camera, monitoring camera, and endoscope), and the microcomputer for controlling the driving operation of the change in image pickup range on the basis of the signal from the apparatus main body. Processing functions for at least the field change operation of the image pickup system are collected together in the image pickup unit.
Accordingly, it is possible to realize a generalized and compact image-pickup unit in which the image pickup range can change and to provide the image pickup unit in various apparatuses.
Incidentally, the image pickup unit may have not only the field-change functions but also processing functions, e.g., zooming, focusing, and exposure correcting operation.
Preferably, the optical system of the image pickup unit according to the present invention may have a stop which is located at the position which is the nearest to the object, or have a stop in the optical system in a manner such that an image through the stop is formed on the side of the object nearer than that of the stop by the portion constructing the optical system thereon at a negative magnification.
Thus, the increase in the optical effective diameter on a plane of incidence can be reduced as compared with the conventional optical system having only a refracting optical device, and this makes it advantageous in that the optical system and the image pickup unit may become compact.
Further objects, features and advantages of the present invention will become apparent from the following description of the preferred embodiments (with reference to the attached drawings).